Internal combustion engines with conventional or computer-controlled engine starting systems can stall or fail to start under certain conditions. For example, after multiple engine start attempts, an engine may become flooded with fuel. A flooded engine may be manually started by fully depressing the accelerator pedal to shut off the fuel injectors while the engine is cranking. However, if a vehicle operator is not familiar with this manual procedure for starting a flooded engine, the vehicle operator may not be able to start the engine.
Various approaches have been developed for reducing engine flooding and/or for improving engine startability of a flooded engine. For example, Nakata et. al. (US Patent Application 2007/0028881) describes measuring crank duration via the number of engine revolutions during cranking, and stopping supply of supplementary fuel to the engine when the number of engine revolutions during cranking exceeds a prescribed number of engine revolutions. Accordingly, an excessive amount of fuel is not supplied to the engine thereby reducing the risk of engine flooding and increasing the possibility of subsequently starting the engine successfully by engine cranking.
The inventors herein have recognized issues with the above approaches. Namely, although supplementary fuel to the engine is stopped, fuel is still supplied to the engine when the crank duration exceeds the prescribed crank duration from a primary fuel supply source. Furthermore, if the engine floods, the vehicle driver must be familiar with manual procedures for starting a flooded engine in order to be able to operate the vehicle.
One approach that at least partially addresses the above issues comprises a method of automatically de-choking an engine and cranking the engine in response to an engine flood event. Automatically de-choking the engine may comprise cutting fuel to the engine while opening an air intake throttle, adjusting the air-fuel ratio to a de-choking air-fuel ratio, and/or extending a cranking duration to increase purging of fuel from the engine. In this manner, a method for de-choking and starting an engine may be automatically performed in response to an engine flood event, thereby increasing engine startability, even when a vehicle driver is unfamiliar with manual procedures for starting a flooded engine.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.